A kqueue descriptor is readable while one of its events is triggered and
is never writable or exceptional, as FreeBSD's kqueue_poll answers, on
both hosts. On Windows select threw for it, and on Linux its /dev/null
placeholder was reported readable and writable.
A descriptor that stops being a socket, a kqueue or a pipe during the
wait now fails the call with EBADF when it was closed and is selected
again with the rest of the timeout when its number was reused, as
FreeBSD's kern_select looks every descriptor up again in each pass,
instead of throwing. On Windows a host descriptor that is not a pipe
throws when select starts, before waiting.
Depends on #7139.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
selscan asks a descriptor once, with the flags of every set it is in (POLLRDNORM for the read set, POLLWRNORM for the write set, POLLRDBAND for the exception set, plus POLLHUP and POLLERR), and marks each set whose flags the answer shares. A seeded random device's randomdev_poll narrows a request with POLLRDNORM to that bit and returns any other request whole, so in the read set it is readable and in no other set, and otherwise it is in each write and exception set it was asked in; select reported it readable and writable together and never exceptional. A regular file or directory went to the host poll, which on Windows threw; vop_stdpoll makes it readable and writable and never exceptional, which select now answers in process on every host, as poll does.
On Windows, select over pipes polls readiness in HostPoll and sleeps
std::this_thread::sleep_for(1 ms) between rounds, and poll with pipes
but no native sockets sleeps sleep_for(slice). winpthreads ends these
sleeps on 15.6 ms timer ticks (#1471), so a guest select or poll with a
short timeout on an idle pipe waits about 15 ms per call instead of its
timeout, and a longer wait checks the pipes only every 15.6 ms.
Both paths now sleep with PreciseSleepUntil. Each sleep requests at
most 1 ms and ends no later than the deadline; the old HostPoll sleep
could pass its deadline by a whole tick. poll on pipes also stops
spinning through the last partial millisecond before its deadline,
where the remaining time truncated to 0 ms and no sleep was made.
Infinite timeouts still sleep 1 ms per round.
The pipes are now checked about every 1.5 ms instead of every 15.6 ms:
a pipe that becomes ready is noticed sooner, and a thread blocked on an
idle pipe wakes about ten times as often. A 1 ms poll on an idle pipe
returns after about 1.5 ms instead of spinning for 1 ms.
guest_poll times 20 polls with a 2 ms timeout on an empty pipe read end
and guest_select times 20 selects with a 1 ms timeout on it; each set
must take less than 200 ms. A 1 ms poll does not reach the old sleep,
because the remaining time truncates to 0 ms and the old loop spins
until the deadline, so the poll check uses 2 ms. On Windows Server 2025
both sets took 312 ms before this change and about 50 ms and 30 ms
after it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
libkernel numbered guest sockets from GuestSockets::FirstDescriptor
(0x10000000), so a title that puts a socket in a 1024-bit fd_set writes
fd / 8 bytes past it. The Epic Online Services SDK does this on its
RtcNetworkThread and three titles stop there (#1794):
Palworld PPSA23126 (queeeef, main a11c8f7f7):
FATAL: unhandled exception 0xc0000005 on thread 37164 'RtcNetworkThread'
rip 0x00007ffcdb1ea2be eossdk-ps5-shipping.prx.guest.prx+0xdea2be
rcx 0000000010000005 rsi 0000000000400000 r12 0000000010000005
The Mound PPSA26223 (xXPBSXx, main 0a8b1d32b):
FATAL: unhandled exception 0xc0000005 on thread 'RtcNetworkThread',
rip eossdk-ps5-shipping.prx.guest.prx+0xefc6f4, rcx = 0x10000005,
rsi = 0x400000
Dying Light 2 PPSA02262 (tv7):
FATAL: unhandled exception 0xc0000005 on thread 'RtcNetworkThread'
rcx 0000000010000005 ... rsi 0000000000400000 ... r12 0000000010000005
On FreeBSD 11.4 (8c639945) FD_SETSIZE is 1024 (sys/sys/select.h:58-59)
and sockets take the lowest free entry of the one process descriptor
table that files use (kern_descrip.c:1643-1660 fdalloc,
uipc_syscalls.c kern_socket through falloc).
Every socket number is now a real host descriptor: a zero-access NUL
handle registered with _open_osfhandle on Windows (as directory
descriptors already are) and an F_DUPFD_CLOEXEC duplicate of the host
socket on Linux. The socket table maps that number to the socket, so
"is this a socket" is a table lookup instead of a range check at the 31
former FirstDescriptor comparisons. close releases both the socket entry
and the number, dup and dup2 duplicate the number through the host table
and keep the socket shared, dup2 of a file onto a socket number drops the
socket entry, and sceKernelClose now closes sockets too. sceNetSocket and
sceNetAccept take their ids from the same table instead of a counter from
32, so libkernel and libSceNet numbers never collide.
select polls guest sockets alongside libSceNet sockets, the random device,
stdio and (on Linux) host descriptors; poll throws only for an open
descriptor that is not a guest socket and reports POLLNVAL otherwise.
File calls that used to fail with EBADF on the socket range return
FreeBSD's answer for a socket: lseek ESPIPE (kern_lseek), ftruncate and
getdirentries EINVAL (invfo_truncate, getvnode), flock EOPNOTSUPP;
fstat on a socket throws. pread on a closed descriptor returns EBADF.
title failing on host descriptor numbers; these three titles are that
case, and this change keeps host numbering for files and only moves
sockets into it.
Tests: guest_socket_descriptors (new: socket below 1024, select on a
socket and a file together, close frees the number for a file, dup of a
socket, sceKernelClose), guest_select (socket and pipe together, Linux),
guest_poll, guest_dup, guest_socket_pair, guest_fstatfs,
guest_posix_filesystem and guest_sce_net updated.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
(cherry picked from commit 20378375b31eb5db922db6e55f45e44a4dae6445)
